Increasingly, advertisers and media placement agencies track the timing and placement of their own advertisements using both manual and automated techniques to verify that the correct ad is aired on the right channel at the right time. Oftentimes, the advertiser will want to monitor the timing and placement of its ads in order to audit what is known in the industry as an “affidavit”. The affidavit is typically received from the broadcaster as a form of invoice detailing which ads were aired at which time. In addition to monitoring the placement and timing of one's own ads, useful competitive intelligence can be gleaned by tracking the ads of competitors.
Prior art techniques for automated monitoring of advertisements on TV, radio, or other broadcast media (e.g. internet) typically require that a fingerprint or watermark be inserted into the ad to enable the ad to be identified. The fingerprint or watermark is designed to be recognizable to a signal analyzer or digital signal processor when specific filters are applied to the signal but without perceptibly distorting the signal, i.e. without degrading the audio or video. Inserting fingerprints or watermarks, however, requires that ads be processed before airing, thus representing an additional expenditure of time and money.
Recognition of broadcast segments without first implanting a fingerprint or watermark is also known in the art. U.S. Pat. No. 3,919,479 to Warren D. Moon, entitled BROADCAST SIGNAL IDENTIFICATION SYSTEM, which issued on Nov. 11, 1975, describes a process for automatic electronic recognition and identification of programs and commercial advertisements broadcast on television and radio wherein a digitally sampled reference signal segment derived from either the audio or video portion of the original program content to be identified is compared with successive digitally sampled segments of the corresponding audio or video portion of a broadcast signal in a correlation process. A signature is generated by sampling a low-frequency envelope of a predetermined size generated from a non-linear analog transform of the audio and video components of the broadcast signal, and digitizing the samples. Unfortunately the number of samples required to characterize the segment makes the signature cumbersome to match, and expensive to store.
Subsequently developed techniques for generating smaller signatures unfortunately characterize the segments poorly. A number of patents have taught signatures generated from one or only a few frames of the segment which does not necessarily mean that a match has been found.
For example, U.S. Pat. No. 6,002,443, entitled METHOD AND APPARATUS FOR AUTOMATICALLY IDENTIFYING AND SELECTIVELY ALTERING SEGMENTS OF A TELEVISION BROADCAST SIGNAL, which issued to Iggulden on Dec. 14, 1999, teaches the use of an average luminance value of select lines of a select frame of the segment. More specifically, 64 consecutive odd lines chosen after line 22 of an NTSC frame, of a 10th frame after a segment transition event, are suggested for this purpose. The suggested signature is a small 64-bit value, one bit defined by each respective line, in relation to a threshold. While the signature is 64 bits long, it does not characterize more than the one frame of the segment, which is insufficient to determine with certainty whether an advertisement is in fact the one that is sought.
Another method of generating a signature for a broadcast segment is taught in U.S. Pat. No. 5,436,653 entitled METHOD AND SYSTEM FOR RECOGNITION OF BROADCAST SEGMENTS, which issued to Ellis on Jul. 25, 1998. This signature generation method involves calculating a difference vectors from average luminance values of pairs of predefined patches of pixels (both active and blanked) of the frame. There are 16 pairs of the patches, and consequently 16 difference values are calculated for each frame. Each of the 16 value difference vectors is subjected to a plurality of vector transformations to generate the signature. The method requires complicated video edge detection, sophisticated vector transformation algorithms designed to improve the differentiation of the resulting signatures, and jitter compensation to adaptively modify a portion of the patches used to generate the averages. While the invention provides a compact signature, the signature is represents only a few frames, which is insufficient to positively identify an ad with a high degree of certainty.
None of the prior art systems characterize a broadcast segment using features relating to its entire length while providing a reasonably-sized signature. Further, known systems fail to reliably distinguish two segments that have similar frame sequences, and misidentify common frame sequences in different segments. There therefore remains a need for a system that is largely immune to a broadcast signal's noise, jitter and instability, that efficiently and accurately characterizes substantially entire segments in order to automatically identify an advertisement with a very high degree of certainty so that automated auditing and verification reports can be generated quickly and accurately. Therefore, improvements to the prior art technology remain highly desirable.